Harbinger Capital Management's wireless Internet venture missed another payment to one of its remaining partners on Saturday, with another looming tomorrow.

Inmarsat, the British satellite company that Harbinger chief Philip Falcone once dreamed of combining with his LightSquared, said that LightSquared missed a $29.6 million payment on March 31, the company's second default in as many months. LightSquared missed a $56.3 million payment in February, Inmarsat said.

Worse still for the struggling LightSquared, which is on life support after U.S. regulators said they would not approve its network plans, another "material" payment is due Inmarsat tomorrow, although Inmarsat said in a statement that further payments from LightSquared are "highly uncertain."

Whether or not LightSquared makes that payment, Inmarsat won't say, writing that today's statement will be its last on the matter of missed payments. LightSquared has previously denied it was in default; Inmarsat said the two sides are in talks about the future of their cooperation agreement.